This invention relates generally to pneumatic plug devices for sealing pipelines or conduits. Particularly, this invention relates to pneumatic test plugs for sealing clean-out tees or access ports of low pressure pipelines or conduits.
Clean-out tees or access ports to pipelines are typically found in drain pipes, such as those located in the main plumbing drain pipes in residential structures. Clean-out tees are also utilized in other horizontally and vertically disposed conduits or pipelines which may require periodic entry for cleaning or inspection purposes. The clean-out tees or access ports are typically circular structures which extend perpendicularly from the pipeline and are internally threaded to receive a threaded closure cap.
The pneumatic clean-out plug device of this invention permits a user to utilize a clean-out tee or access port and to seal the pipeline for purposes of testing the pipeline for leakage, pressure testing, or the like. The pneumatic test plug of the invention is designed to use the internal threads of the clean-out tee for securement purposes.
Although various plugs, including pneumatic plugs, have been used and proposed in the past for sealing clean-out tees, they have typically been complex structures which have been difficult and costly to manufacture. For example, U.S. Pat. No. 4,658,861 to Roberson discloses a test plug assembly for pressure testing fluid drains and vent systems. The '861 plug assembly utilizes an inflatable body and a rigid holder portion which are united by means of a valve stem. The configuration of the '861 assembly is difficult and expensive to manufacture. The materials required to properly unite the inflatable body to the rigid holder portion requires a relatively harder elastomeric material which may compromise proper sealing of the plug assembly in certain conduit structures.
The pneumatic test plugs for clean-out tees according to the teachings of this invention overcome the difficulties, limitations and other shortcomings of these prior art devices.